The present invention relates to the art of tomographic imaging. It finds more particular application in 3D and 2D tomographic imaging based on one or more layers in a human body being measured by an x-ray system. However, it will be appreciated that the invention has other applications such as imaging of an object with other types of penetrating radiation to determine the make up and constituent components of that object and it may be advantageously employed in other environments and applications.
Traditionally, x-rays are projected from an x-ray source and through an object for exposing an image onto x-ray film. The image is typically a compression of all of the structures in the imaged portion of the body exposed onto the x-ray film. The vast amount of superimposed information can make diagnosis difficult.
In one technique for emphasizing a selected plane of the object, the x-ray source and the x-ray film move contra-cyclically in parallel planes which are parallel to the plane of interest. More specifically, the x-ray source and the x-ray film are moved such that the ray which exposes each incremental element of the x-ray film pivots about a fixed point in the plane of interest or focal plane. In this manner, each incremental element of the x-ray film is consistently exposed by radiation passing through a constant point in the focal plane. However, because the ray is pivoting about the constant point, the same increment of x-ray film is also exposed by a variety of structures outside the focal plane. In this manner, information from structures outside of the focal plane become blurred on the same x-ray film on which image data attributable to structures on the focal plane remains sharp and crisp.
If the diagnostician wishes to view another selected plane, the position of the patient is shifted relative to the x-ray source and the x-ray film canister such that the focal plane passes through a different selected plane of the object. With sufficient time, a series of parallel planer film images can be generated through the object. However, because each image takes a significant amount of time to generate, there is a significant temporal offset or time evolution among the images.
The temporal offset can be greatly reduced with volumetric CT scanners. However, CT scanners are not only much larger and more complex then the traditional x-ray film imaging systems, they are also much more expensive. Moreover, CT scanners are a different piece of equipment often positioned in a different room or location within the facility and in some instances at a different facility completely. Typically, the CT scanners are operated by different technicians. Accordingly, there are time delays in transporting the patient from one piece of equipment to the other, sometimes involving the making of additional appointments. Thus, the film images and the CT images may have very large temporal offsets. Moreover, it is difficult to maintain the position and orientation of the patient constant during such transporting. Accordingly, the resultant CT images are often not of the same physiology as the film images.
The present invention contemplates a new and improved apparatus and method which overcomes the above-referenced problems and others.